Plastic encapsulated semiconductor devices have proven to be reliable and economical to manufacture. Accordingly, they have become quite common. Typically, the semiconductor device is connected by way of a copper lead frame that provides a mounting base and contact pad connections. After the semiconductor device is mounted upon the lead frame and the bond pad interconnections made, a suitable plastic encapsulant is transfer molded around the lead frame so that flat metal leads extend as pins outward from the package. These pins can be bent to a suitable configuration for attachment to a printed wiring board or equivalent.
In the prior art when a copper lead frame is employed the parts that will contact the semiconductor device are coated with a suitable noble metal such as gold or silver. Since such metals are quite expensive it has been a common practice to spotplate the lead frame to preclude metal deposition in areas where no contact is to be made. This requires some form of masking and only reduces costly metal use. The noble metal coating is still employed. It would be highly desirable, from a cost standpoint, to totally eliminate the noble metal.